Is there any comprehensive reference for Almos-Kahler geometry or more generally to Almost- Hermitian geometry ?
The paper that started this all is the one by Gray and Hervella where they classified the different types of almost Hermitian structures. It's a classic and still very much well worth reading:
The sixteen classes of almost Hermitian manifolds and their linear invariants.
A Gray, LM Hervella.
Ann. Mat. Pura Appl. (4) (1980) vol. 123 pp. 35-58
A slightly more current paper can be found here:
Apostolov, Vestislav; Drăghici, Tedi The curvature and the integrability of almost-Kähler manifolds: a survey. Symplectic and contact topology: interactions and perspectives (Toronto, ON/Montreal, QC, 2001), 25–53, Fields Inst. Commun., 35, Amer. Math. Soc., Providence, RI, 2003.
This gives a review of the various approaches to Almost Kaehler Geometry that has been taken since the Gray/Hervella article.